Criticism, how not to do it?

A friend of mine reads a blog by a guy named Seth Godin. I haven't read too much of it, occasional posts which my friend links to. I don't know much about Mr. Godin or where he's coming from, but he's got a blog, and people read it, and that's cool. I read a post just now (which my friend had linked, and which I've linked above) in which Godin warns off of criticizing the choices people make. Specifically he seems to be talking about criticizing the past choices a prospective client or prospective employee has made.

I looked around the post for a while and could not find a "comment" button, which I found a little odd (isn't 1/2 of blogging all about getting and responding to comments?), so I decided to post here in my blog to as a question which came up in my mind:

If criticizing someone's choices will make them less likely to trust my judgment because I just questioned theirs (that's Godin's assertion) - How do you approach someone who is contemplating a choice you think is bad? Maybe this is your spouse about to spend too much money on an unnecessary novelty for example, or a business partner about to make a business deal you think is bad. Or just a friend who tells you he's got this great idea which you think would turn out terribly?

Godin suggests that instead of criticizing past choices, the prospective employer (or whoever) would be better off complementing the bad-choice-maker for making what at the time must have been exactly the right choice. I can't really argue with that, people like to be placated and complemented. But outside the narrow circumstance he's discussing, where it's helpful from a marketing perspective for the placatee to think highly of you, I don't find that advice very helpful. I'll certainly keep it in mind for when I'm in that circumstance, because I agree that's a diplomatic and polite way to behave, but more often (especially recently) I find myself in different circumstances than that.

Anyone have thoughts on that?